Musnad Ahmad 1159:8

Muhammad ibn Ja‘far narrated to us, he said: Shu‘bah narrated to us, and Hajjaj said: Shu‘bah narrated to me, from Humayd ibn Nafi‘, who said: I heard Zaynab bint Umm Salamah say: A relative of Umm Habibah died, so she called for some yellow perfume and wiped it on her forearms. She said: I am only doing this because of something I heard the Messenger of Allah (ﷺ) say. Hajjaj said: Because the Messenger of Allah (ﷺ) said: "It is not permissible for a Muslim woman who believes in Allah and the Last Day to mourn for more than three days, except for her husband, for four months and ten days." Zaynab narrated it from her mother, and from Zaynab, the wife of the Prophet (ﷺ), or from a woman, one of the wives of the Prophet (ﷺ).